What is Ultraviolet (UV) radiation and the SunSmart UV Alert?

Ultraviolet (UV) radiation is a form of energy that is produced by the sun. Our sun produces different kinds of energy:

  • Visible light that we can see (sunlight)
  • Infrared red radiation that we can feel (heat or temperature); and
  • UV radiation that we can’t see or feel.UV sources

UV radiation is often confused with infrared radiation. The temperature, however, does not affect UV radiation levels. UV radiation can be just as high on a cool or even cold day as it is on a hot one, especially if skies are clear. Thick cloud provides a good filter, but UV radiation can penetrate thin cloud cover. And while UV radiation is higher in summer than in winter, it is still present every day of the year.

There are three types of UV radiation:

UVA: transmits freely through the earth’s atmosphere.
UVB: about 15% of UVB transmits through to the earth’s atmosphere. The rest is absorbed by ozone.
UVC: is absorbed by ozone and does not reach the earth’s surface.

UVA and UVB both contribute to sunburn, skin ageing, eye damage and skin cancer.

UV radiation from the sun is the cause of almost all skin cancers. The simplest way to reduce your risk of melanoma and other skin cancers is to use sun protection when the sun’s rays are strong enough to damage your skin.

Unfortunately you can’t see or feel UV radiation so it can be difficult to know when you need to use sun protection. Not only is UV radiation present every day (even on cold days) but UV levels change according to a number of factors. These include:

  • time of year
  • time of day
  • geographical location
  • cloud cover

Download the SunSmart app

The SunSmart App will show you the daily UV levels, set a sunscreen reminder and track your vitamin D intake.

SunSmart app for Android
SunSmart app for iPhone


The SunSmart UV Alert is a useful tool that identifies:

  • The hours of each day when the UV Index will be 3 or above – that is high enough to cause permanent damage to most skin types.
  • The maximum UV forecast for the day.
  • The SunSmart UV Alert uses the UV Index to demonstrate how UV levels rise and drop throughout the day.

The UV Index:

  • Divides UV radiation levels into: low (1-2), moderate (3-5), high (6-7), very high (8-10) and extreme (11 and above).
  • Is often presented in the shape of a bell curve to show how UV radiation levels change throughout the day – lower in the morning, highest in the middle part of the day and gradually dropping again throughout the afternoon.

How to read the SunSmart UV Alert
Uv Alert exampleIn the example below the SunSmart UV Alert sun protection times are from 9am to 3.20pm. This means that between these times UV levels will be 3 and above – strong enough to cause permanent damage to most skin types – and sun protection should be used.

UV levels vary across different parts of NSW. Even on the same day UV levels will be higher in some parts of NSW than in others.

You can check the SunSmart UV Alert daily on www.sunsmart.com.au/uvalert/, in most local newspapers or by downloading the free SunSmart App (above). You can also add the UV Alert to your widget to your website.